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🛠️ Aligner Tool

Available from v2.1.0

This powerful tool allows you to align, rotate, and scale vector features (lines or polygons) with precision. It works by mapping two "source" vertices from your feature to two "target" points on the map, similar to a two-point georeferencing operation.

✅ Prerequisites​

  • An editable Line or Polygon layer must be the active layer in QGIS.
  • The layer must be in editing mode (pencil icon ✏️ activated).
  • For best results, enable snapping in Project > Snapping Options... to accurately select points and vertices.

🔄 Tool Workflow Overview​

The tool follows a simple 4-click sequence to define the transformation:

  1. Click 1 (Source Vertex 1): Select the vertex on your feature that should move to Target Point 1.
  2. Click 2 (Target Point 1): Select the destination point on the map.
  3. Click 3 (Source Vertex 2): Select the second vertex on your feature that should move to Target Point 2.
  4. Click 4 (Target Point 2): Select the second destination point.
  5. Choose Operation: A dialog will ask if you want to Scale the feature to fit the new points or just Align Only (move and rotate).
  6. Transformation Applied: The feature is moved, rotated, and optionally scaled. The tool automatically resets and is ready for another alignment.

Note: At any time during the process, right-click to reset the tool and start a new alignment action.

🧭 Step-by-Step Instructions​

🟩 Step 1: Activate the Tool​

  1. Make sure your desired line or polygon layer is active and in editing mode.
  2. Activate the Aligner Tool from the plugin toolbar or menu.
  3. A message will appear:

    "Tool activated... Left-click to select points, right-click to reset."

🟩 Step 2: Select the First Pair of Points​

  1. Select Target Point 1: Left-click on the map where you want the first vertex to end up. You can snap to any existing geometry for precision.

    • A red point marker will appear.
    • The message bar will prompt: "First point selected. Select the corresponding feature vertex."

  2. Select Source Vertex 1: Left-click on the vertex of the feature you want to align. This is the point that will be moved to your first target point.

    • A blue dashed line will appear, connecting the target point to the source vertex.
    • The message bar will prompt: "First vertex detected... Select the second target point."

🟩 Step 3: Select the Second Pair of Points​

  1. Select Target Point 2: Left-click on the map to define the second destination point.

    • A second red point marker will appear.
    • The message bar will prompt: "Second target point selected... Select the second vertex from source layer."

  2. Select Source Vertex 2: Left-click on the second vertex of your feature.

    • A second blue dashed line will appear.

🟩 Step 4: Choose the Alignment Operation​

Immediately after the fourth click, a dialog box titled "Align Tool - Choose Operation" will appear with three buttons:

  • Scale: This will translate, rotate, and scale the feature. The distance between the two source vertices will be adjusted to match the distance between the two target points.
  • Align Only: This will only translate and rotate the feature. The size and shape of the feature will be preserved.
  • Cancel: Aborts the current operation.

🟩 Step 5: Review and Continue​

  • After you make a choice, the feature is instantly transformed.
  • The tool automatically resets and is ready for a new alignment operation, starting again from Step 2.

💡 Tips and Additional Features​

  • Multi-Feature Alignment: If you have multiple features selected in the layer before starting the alignment process, the same transformation will be applied to all of them.
  • Resetting: A right-click at any time will cancel the current point selection and reset the tool, allowing you to start over.
  • Snapping: This tool fully respects your project's snapping settings. Enable snapping to vertices and segments for the most accurate selections.
  • Visual Feedback:
    • Red Points: Your target destination points.
    • Blue Dashed Lines: Show the mapping from your source vertices to your target points.
    • Snap Indicator: A magenta cross shows when you are snapped to a vertex or segment.

🛑 To Exit the Tool​

Simply select any other tool from the QGIS toolbars (like the Pan or Select tool). The Aligner Tool will automatically deactivate.